Chapter 7 Lesson 2 Pages 274-281

Igneous rock is rock that is formed when melted rock hardens.

Magma is melted rock inside the Earth.

Lava is melted rock at the Earth’s surface.

Crystallization is the hardening of magma into rock.

Intrusive rock cools underground, deep within the Earth’s crust.

Characteristics of intrusive igneous rock: --Intrusive rocks cooled slowly. --Intrusive rocks have large crystals. --These rocks have coarse texture.

Examples: Granite and Diorite

Granite

Diorite

Extrusive igneous rock is rock that cools on the Earth’s surface.

Extrusive rock cools quickly on the surface.

Extrusive rock has fine grains or even no crystals at all and

looks glassy

Examples: Obsidian, Pumice and Rhyolite

Obsidian

Igneous

Rhyolite

Pumice

Sedimentary rock is rock that forms when layers of sediment settle and bind together.

There are two main groups of sedimentary rock,Clastic and Chemical

Clastic-The word comes from the Greek word that means “broken”.

Process begins when rock is broken through weathering.

Wind and water move sediment to new places, layers build up; minerals bind layers.

Layers are pressed and cemented together.

Clastic rocks are classified by size of particle.

Examples of clastic sedimentary rock

Fine particles form shale.

Medium particles form sandstone.

Coarse pebble-sized particles with smooth edges form conglomerates.

Sedimentary

Sandstone

Chemical sedimentary rocks form when chemicals in water come out of the water (evaporate) and form solids.

Example: Limestone (may contain fossils)

- Meta means “change”.

How metamorphic rock is made:

Igneous or sedimentary rock is changed by

PRESSURE

HEAT – high temperature, very hot water

BOTH

Metamorphism is the process by which rock is changed into metamorphic rock.

The main cause is high temperature-deep inside the Earth or in lava/magma.

Minerals melt and then crystallize into new minerals.

Regional Metamorphism takes place over a large area

Mountain building

Contact metamorphism changes a smaller area by magma or lava touching rock and changing the rock that was touched.

Examples

Shale becomes SLATE.

Slate becomes SCHIST.

Schist becomes GNEISS.

Limestone becomes MARBLE.

Shale becomes SLATE.

Slate becomes SCHIST.

Schist becomes GNEISS.

Limestone becomes MARBLE.

Rock Use

Granite Buildings

Sandstone Glass

Obsidian Jewelry, blades (in history)

Pumice Cleaning products

Shale Construction

Mudstone Construction

Marble Buildings and sculptures

Slate Roofs, floors, chalkboards